Study On The Isolation And Identification Of Primary Pahtogenic Bacterium In Storage Period Of Tender Ginger And Inhibitory Effect Of Several Essential Oils To These Bacterium

The research took the moldy ’Beichuan’ ginger during storage as test materials and we isolated and identificated the pathogens which easily led to mildew in the storage process. Its biological characteristics were researched and the antibacterial effect of several essential oils on pathogenic were explored. The main results were as follows:1. Three pathogens in ginger(IS496、IS498 and IS497) which can lead to mildew were found. According to morphological features and 18S rDNA sequences analysis, the strains were identified as Penicillium sp.,Fusarium culmorum and Mortierella.2. It is proved that the optimum growth temperature of Penicillium is 20℃, the optimum pH is 7, spores begin to grow if the relative humidity is above 88% and the ratio of gemination can be up to 15.13%. Light has no significant effect on the growth and sporulation of Penicillium, its optimal growth carbon source is sucrose and its optimal growth nitrogen source is NH4NO3 or beef extract. The optimum growth temperature of Fusarium culmorum is 20℃, the optimum pH is 8 and spores begin to grow if the relative humidity is above 80% and the ratio of gemination can be up to 83.81%. Fusarium culmorum grows better under full light conditions, its optimal growth carbon source is maltose, optimal growth nitrogen source is peptone. The optimum growth temperature of Mortierella is 20℃, the optimum pH is 6 and spores begin to grow more than 75% in relative humidity and can up to 48.08%. The better growth condition of Mortierella is completely dark, its optimal growth carbon source is maltose or glucose. There are no significant differences between beef extract, ammonium nitrate and peptone in the growth of Mortierella. Under these nitrogen sources, the Mortierella grows better.3. It is proved in the research that several essential oils inhibit the growth of pathogens bacteria, the inhibitory effect of cinnamon essential oil for three pathogens is the best, the inhibition zone can be reached 85mm. Clove oil, thyme oil and basil oil also have good inhibitory effect to these pathogens, the inhibition zone of these essential oils in Penicillium are 29.75mm,85mm and 35.29mm. The Fusarium’s inhibition zone of these essential oils can be reached 37.32mm,85mm and 42.77mm. The Mortierella’s inhibition zone of these essential oils are 14.76mm,34.25mm and 16.16mm.4. To determine the minimum inhibitory concentration (MIC) after inoculation for 48h and the minimum inhibitory concentration (MIC) after inoculation for 96h:the Penicillium,Fusarium culmorum and Mortierella’s MIC of cinnamon essential oil are 78.13μL/L,39.06μL/L and 19.53μL/L, MBC are 156.25μL/L,39.06μL/L and 19.53μL/L. The MIC of Penicillium、Fusarium and Mortierella under clove oil are 1250μL/L, 1250μL/L and 2500μL/L and the MBC are the same. The MIC of Penicillium,Fusarium culmorum and Mortierella under thyme essential oils are 2500pL/L,312.5μL/L and 1250μL/L and the MBC are the same. The MIC of basil oil in Penicillium, Fusarium culmorum and Mortierella are 1250μL/L,625μL/L and 625μL/L and the MBC are 1250μL/L.